Be less verbose when printing Names when we don't know what's in scope

Previously we always printed qualified names, but that makes a lot of debug or
warning output very verbose. So now we only print qualified names with -dppr-debug.

Civilised output (from pukka error messages, with the environment available) is
unaffected

2 files changed, 13 insertions, 14 deletions

diff --git a/compiler/stranal/WwLib.lhs b/compiler/stranal/WwLib.lhs
index 68292839ed..4610b58734 100644
--- a/compiler/stranal/WwLib.lhs
+++ b/compiler/stranal/WwLib.lhs
@@ -732,7 +732,7 @@ mk_absent_let dflags arg
   where
     arg_ty  = idType arg
     abs_rhs = mkRuntimeErrorApp aBSENT_ERROR_ID arg_ty msg
-    msg     = showSDocDebug dflags (ppr arg <+> ppr (idType arg))
+    msg     = showSDoc dflags (ppr arg <+> ppr (idType arg))
 
 mk_seq_case :: Id -> CoreExpr -> CoreExpr
 mk_seq_case arg body = Case (Var arg) (sanitiseCaseBndr arg) (exprType body) [(DEFAULT, [], body)]
diff --git a/compiler/utils/Outputable.lhs b/compiler/utils/Outputable.lhs
index e8d9347767..85d3d03557 100644
--- a/compiler/utils/Outputable.lhs
+++ b/compiler/utils/Outputable.lhs
@@ -190,31 +190,30 @@ neverQualify  = (neverQualifyNames,  neverQualifyModules)
 
 defaultUserStyle, defaultDumpStyle :: PprStyle
 
-defaultUserStyle = mkUserStyle alwaysQualify AllTheWay
+defaultUserStyle = mkUserStyle neverQualify AllTheWay
+ -- Print without qualifiers to reduce verbosity, unless -dppr-debug
 
 defaultDumpStyle |  opt_PprStyle_Debug = PprDebug
                  |  otherwise          = PprDump
 
+defaultErrStyle :: DynFlags -> PprStyle
+-- Default style for error messages, when we don't know PrintUnqualified
+-- It's a bit of a hack because it doesn't take into account what's in scope
+-- Only used for desugarer warnings, and typechecker errors in interface sigs
+-- NB that -dppr-debug will still get into PprDebug style
+defaultErrStyle dflags = mkErrStyle dflags neverQualify
+
 -- | Style for printing error messages
 mkErrStyle :: DynFlags -> PrintUnqualified -> PprStyle
 mkErrStyle dflags qual = mkUserStyle qual (PartWay (pprUserLength dflags))
 
-defaultErrStyle :: DynFlags -> PprStyle
--- Default style for error messages
--- It's a bit of a hack because it doesn't take into account what's in scope
--- Only used for desugarer warnings, and typechecker errors in interface sigs
-defaultErrStyle dflags = mkUserStyle alwaysQualify depth
-    where depth = if opt_PprStyle_Debug
-                  then AllTheWay
-                  else PartWay (pprUserLength dflags)
+cmdlineParserStyle :: PprStyle
+cmdlineParserStyle = mkUserStyle alwaysQualify AllTheWay
 
 mkUserStyle :: PrintUnqualified -> Depth -> PprStyle
 mkUserStyle unqual depth
    | opt_PprStyle_Debug = PprDebug
    | otherwise          = PprUser unqual depth
-
-cmdlineParserStyle :: PprStyle
-cmdlineParserStyle = PprUser alwaysQualify AllTheWay
 \end{code}
 
 Orthogonal to the above printing styles are (possibly) some
@@ -979,7 +978,7 @@ assertPprPanic file line msg
 
 pprDebugAndThen :: DynFlags -> (String -> a) -> String -> SDoc -> a
 pprDebugAndThen dflags cont heading pretty_msg
- = cont (showSDocDebug dflags doc)
+ = cont (showSDoc dflags doc)
  where
      doc = sep [text heading, nest 4 pretty_msg]
 \end{code}